Radiation Oncology Virtual Education Rotation (ROVER) 2.0 for Residents: Implementation and Outcomes

The COVID-19 pandemic catalyzed the integration of a virtual education curriculum to support radiation oncologists in training. We report outcomes from Radiation Oncology Virtual Education Rotation (ROVER) 2.0, a supplementary virtual educational curriculum created for radiation oncology residents globally. A prospective cohort of residents completed surveys before and after the live virtual webinar sessions (pre- and post-surveys, respectively). Live sessions were structured as complex gray-zone cases across various core disease sites. Resident demographics and responses were summarized using means, standard deviations, and proportions. Nine ROVER sessions were held from October 2020 to June 2021. A total of 1487 registered residents completed the pre-survey, of which 786 attended the live case discussion and 223 completed post-surveys. A total of 479 unique radiation oncology residents (of which 95, n = 19.8%, were international attendees) from 147 institutions (national, n = 81, 55.1%; international, n = 66, 44.9%) participated in the sessions. There was similar participation across post-graduate year (PGY) 2 through 5 (range n = 86 to n = 105). Of the 122 unique resident post-surveys, nearly all reported learning through the virtual structure as "very easy" or "easy" (97.5%, n = 119). A majority rated the ROVER 2.0 educational sessions to be "valuable or "very valuable" (99.2%, n = 121), and the panelists-attendee interaction as "appropriate" (97.5%, n = 119). Virtual live didactics aimed at radiation oncology residents are feasible. These results suggest that the adoption of the ROVER 2.0 curricula may help improve radiation oncology resident education.

Radiopharmaceuticals as Novel Immune System Tracers

Immune checkpoint inhibitors (ICIs) have transformed the treatment paradigms for multiple cancers. However, ICI therapy often fails to generate measurable and sustained antitumor responses, and clinically meaningful benefits remain limited to a small proportion of overall patients. A major obstacle to development and effective application of novel therapeutic regimens is optimized patient selection and response assessment. Noninvasive imaging using novel immunoconjugate radiopharmaceuticals (immuno–positron emission tomography and immuno-single-photon emission computed tomography) can assess for expression of cell surface immune markers, such as programmed cell death protein ligand-1 (PD-L1), akin to a virtual biopsy. This emerging technology has the potential to provide clinicians with a quantitative, specific, real-time evaluation of immunologic responses relative to cancer burden in the body. We discuss the rationale for using noninvasive molecular imaging of the programmed cell death protein-1 and PD-L1 axis as a biomarker for immunotherapy and summarize the current status of preclinical and clinical studies examining PD-L1 immuno–positron emission tomography. The strategies described in this review provide insight for future clinical trials exploring the use of immune checkpoint imaging as a biomarker for both ICI and radiation therapy, and for the rational design of combinatorial therapeutic regimens.

Intravesical Anti-PD-1 Immune Checkpoint Inhibition Treats Urothelial Bladder Cancer in a Mouse Model

PURPOSE

Nonmuscle-invasive bladder cancer is treated by resection within the bladder and bladder instillment with bacillus Calmette-Guérin or chemotherapy. For bacillus Calmette-Guérin-refractory disease, systemic anti-PD-1 (programmed cell death protein 1) immune checkpoint inhibition is a treatment. Our aim is to test whether intravesical instillment with anti-PD-1 inhibitor treats localized bladder cancer as effectively as systemic administration.

MATERIALS AND METHODS

We investigated an orthotopic mouse model of urothelial bladder cancer using MBT2 cells instilled into the bladders of syngeneic, wild-type C3H mice. Groups of 10 mice received each treatment for comparison of intravesical anti-PD-1, intraperitoneal anti-PD1, and intravesical chemotherapy. The primary outcome was overall survival and secondary outcomes included long-term immunity and toxicity.

RESULTS

Anti-PD-1 administered by bladder instillment (intravesical route) successfully treats localized bladder cancer and has similar overall survival to anti-PD-1 by systemic route. Anti-PD-1 by either route provides a significant survival advantage over control antibody. Anti-PD-1 increases CD8+ cell infiltration in tumors, particularly when administered intravesically. Antibody treatment avoids toxicity observed for intravesical chemotherapy. Mice who cleared their tumors after initial treatment were rechallenged with tumor engraftment 3-9 months later without any additional treatment. Initial anti-PD-1-treated mice did not grow tumors when rechallenged, which suggests long-term immunity exists, but initial mitomycin-treated mice readily grew tumors indicating no immunity occurred by chemotherapy treatment.

CONCLUSIONS

Intravesical administration of anti-PD-1 is a promising treatment route for localized bladder cancer, with comparable overall survival to systemic anti-PD-1 in this mouse model. Intravesical anti-PD-1 increases CD8+ T cells in treated tumors and long-term immunity was seen to tumor rechallenge.

Inhibition of PIM kinase with fractionated radiation and docetaxel in preclinical prostate cancer models

e17534

Background: PIM kinases are highly expressed in high risk prostate cancer and are associated with aggressiveness and poor prognosis, presenting a therapeutic target. Methods: We studied PIM inhibition (PIMi) in both hormone-dependent (LNCaP) and -independent (DU145, 22Rv1) prostate cancer cell lines and mouse xenografts. We evaluated PIMi effects via Western blotting, immunofluorescence, and RNAseq of multiple relevant pathways, and performed radiosensitization analysis with colony formation assays. We also investigated xenograft tumor growth with PIMi +/- radiation (RT) or docetaxel. Results: Pretreating the cell lines with PIMi prior to RT caused marked changes in H2AX phosphorylation compared to no PIMi + RT, with most significant alteration in DU145. However, in colony formation assays, 22Rv1 showed greatest radiosensitization with colony survival reduced from 23% to 15% with PIMi. 22Rv1 xenografts were grown in castrated mice, which were randomized to 30 Gy in 15 treatments vs no RT over 3 weeks, -/+ PIMi on RT days. RT + PIMi eliminated gross tumor, compared to an average of 78% and 51% of initial tumor volumes remaining with PIMi alone and RT alone, respectively. Immunofluorescence and Western blotting of harvested tumors showed PIMi altered patterns in proteins involved with hypoxic response (COX-2), cell survival (MDM2), and androgen receptor and suggested interactions between RT and PIMi for both MDM2 and androgen receptor but not COX-2. RNAseq analysis of xenografts showed daily PIMi affected multiple pathways involved in metabolism, growth, and DNA repair. Finally, we tested PIMi -/+ docetaxel in castrated mice with hormone-sensitive (LNCaP) or -resistant (22Rv1) xenografts treated with PIMi -/+ docetaxel. With both xenografts, PIMi + docetaxel reduced tumor size best, with 22Rv1 xenografts most dramatically showing 74% volume reduction from baseline with PIMi + docetaxel compared to 50% and 25% reduction in volumes with PIMi alone and docetaxel alone, respectively. Conclusions: PIMi has multiple pathway effects in prostate cancer. PIMi significantly reduces disease burden, particularly in combination with RT or docetaxel. Our data provide rationale for testing PIMi in clinical trials for prostate cancer.